## VINCIA QED Antenna Shower Settings

Here, parameters specific to VINCIA's QED antenna shower are collected. See the main VINCIA antenna shower page for more general parameters that are common to both the QCD and QED showers.

### Main Switches

`flag` Vincia:doQED (`default = on`)
Main switch for QED evolution on/off.

`mode` Vincia:nGammaToQuark (`default = 5`; `minimum = 0`; `maximum = 6`)
Number of allowed quark flavours in final-state photon splitting.

`mode` Vincia:nGammaToLepton (`default = 3`; `minimum = 0`; `maximum = 3`)
Number of allowed lepton flavours in final-state photon splitting.

`flag` Vincia:convertGammaToQuark (`default = on`)
Allow incoming photons to backwards-evolve into (anti)quarks during the initial-state shower evolution.

`flag` Vincia:convertQuarkToGamma (`default = on`)
Allow incoming (anti)quarks to backwards-evolve into photons during the initial-state shower evolution.

### The QED coupling in the Vincia Shower

`mode` Vincia:alphaEMorder (`default = 1`; `minimum = 0`; `maximum = 1`)
`option` 0 : zeroth order, i.e. αem is kept fixed.
`option` 1 : first order, i.e., one-loop running.

`parm` Vincia:alphaEM0 (`default = 0.00729735`; `minimum = 0.0072973`; `maximum = 0.0072974`)
The alpha_em value at vanishing momentum transfer (and also below m_e).

`parm` Vincia:alphaEMmZ (`default = 0.00781751`; `minimum = 0.00780`; `maximum = 0.00783`)
The alpha_em value at the M_Z mass scale.

### Lower Cutoffs for the QED evolution

`parm` Vincia:QminChgQ (`default = 0.5`; `minimum = 0.1`; `maximum = 2.0`)
Parton shower cut-off scale for photon coupling to coloured particle.

`parm` Vincia:QminChgL (`default = 1e-6`; `minimum = 1e-10`; `maximum = 2.0`)
Parton shower cut-off scale for pure QED branchings. Assumed smaller than (or equal to) QminChgQ.

### Other QED Settings

`mode` Vincia:photonEmissionMode (`default = 1`; `minimum = 1`; `maximum = 2`)
`option` 1 : Pairing algorithm
`option` 2 : Coherent algorithm

`flag` Vincia:fullWkernel (`default = on`)
Switch to incorporate the full antenna function for W radiation. If disabled, a W radiates as if it were a lepton.

`parm` Vincia:mMaxGamma (`default = 10.`; `minimum = 0.001`; `maximum = 5000.0`)
Maximum invariant mass allowed for the created fermion pair by photon splitting in the shower.